Synthesis of highly-textured ZnO films on different substrates by hydrothermal route

In this study, we used as-grown ZnO films fabricated by pulsed laser deposition (PLD) which are more flexible in substrates selection as the ZnO seed layers. Thicker highly-textured ZnO films were grown by hydrothermal process on quartz or Si (100) substrates. It has been observed that completely coalesced and smooth films with better c-axis orientation but random in-plane alignment are formed on Si substrates, while the ZnO films on quartz substrates consist of discontinuous hexagonally shaped ZnO rods and exhibit a weak epitaxial in-plane orientation. The optical and electrical properties of the ZnO films were also investigated. A thermal treatment at 400 °C in air for 1 h could improve crystallinity of the ZnO films. This study lays the foundation for growing high-quality and thick ZnO films with large area on various substrates, which could be a promising technique for practical applications.